Self-heating personal covering

ABSTRACT

Disclosed is a self-heating personal covering that includes a first layer and a second layer that is parallel to and opposite of the first layer, and at least a portion of the second layer is fastened to at least a portion of the first layer. The self-heating personal covering also includes at least one heat source positioned between the first layer and the second layer. The at least one heat source is held in a prescribed position by the first layer and the second layer, and includes a material that undergoes an exothermic reaction upon exposure to oxygen. The at least one heat distributing structure is thermally connected to the at least one heat source.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Application No. 62/550,300 filed on Aug. 25, 2017, the entire contents of which are incorporated by reference herein.

TECHNICAL FIELD

The present specification generally relates to self-heating blankets or garments and, more specifically, to self-heating blankets or garments having integrated heating sources and materials that disperse heat within in the blanket or garment.

BACKGROUND

Personal coverings used in medical settings—such as, for example, blankets, garments, gowns, wrappings, and dressings—are often heated using external sources, such as electrical heating, forced air heating, or pre-heating by conduction. However, electrically heated and forced air heated personal coverings are not easily transportable and can be costly to manufacture and maintain. In particular, forced air heated personal coverings require equipment to operate that is expensive and is not easily transported, while the electrical requirements for an electrically heated personal covering may not be available during patient transport. Further, pre-heated personal coverings such as cotton blankets pre-warmed in a warming cabinet will lose heat at an unacceptable rate requiring one to use multiple personal coverings to improve patient comfort and to maintain a patient's body temperature.

Accordingly, a need exists for an alternative self-heating personal coverings that are transportable and provide quick and evenly-distributed heating to the personal covering.

SUMMARY

According to embodiments, a self-heating personal covering includes a first layer and a second layer that is parallel to and opposite of the first layer, and at least a portion of the second layer is fastened to at least a portion of the first layer. The self-heating personal covering also includes at least one heat source positioned between the first layer and the second layer. The at least one heat source is held in a prescribed position by the first layer and the second layer, and includes a material that undergoes an exothermic reaction upon exposure to oxygen. The at least one heat distributing structure is thermally connected to the at least one heat source.

In at least one embodiment, the at least one heat distributing structure comprises an insulating material. The insulating material may be incorporated into the first layer, or the insulating material may be included as an insulating layer. The insulating layer may comprise channels that permit oxygen to access the heat source. In embodiments comprising an insulating layer, the at least one heat source comprises a first heat source and a second heat source, and a gap comprising air is present in between the first heat source and the second heat source. A portion of the insulating layer is positioned proximate to the first heat source, the second heat source, and the gap such that heat is directed into the gap between the first heat source and the second heat source.

In at least another embodiment, the at least one heat distributing structure comprises a thermally conductive material. In embodiments comprising a thermally conductive material, the at least one heat source comprises a first heat source and a second heat source spaced apart from the first heat source, and the thermally conductive material is positioned between and thermally connected to the first heat source and the second heat source.

In at least another embodiment, the at least one heat distributing structure is a layer of phase change material. The layer of phase change material may be positioned between the at least one heat source and the second layer. In such embodiments, the at least one heat source comprises a first heat source and a second heat source, a gap comprising air is present in between the first heat source and the second heat source, and a portion of the layer of phase change material is positioned proximate to the first heat source, the second heat source, and the gap such that heat is directed into the gap between the first heat source and the second heat source.

Additional features and advantages will be set forth in the detailed description which follows, and in part will be readily apparent to those skilled in the art from that description or recognized by practicing the embodiments described herein, including the detailed description which follows, the claims, as well as the appended drawings.

It is to be understood that both the foregoing general description and the following detailed description describe various embodiments and are intended to provide an overview or framework for understanding the nature and character of the claimed subject matter. The accompanying drawings are included to provide a further understanding of the various embodiments, and are incorporated into and constitute a part of this specification. The drawings illustrate the various embodiments described herein, and together with the description serve to explain the principles and operations of the claimed subject matter.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 schematically depicts a top view of a self-heating personal covering according to embodiments disclosed and described herein;

FIG. 2 schematically depicts a cross-section view of a self-heating personal covering according to embodiments disclosed and described herein;

FIG. 3 is a graph showing the performance of self-heating materials;

FIG. 4 schematically depicts a top view of a self-heating personal covering according to embodiments disclosed and described herein;

FIG. 5A schematically depicts a cross section view of a self-heating personal covering comprising an insulating layer according to embodiments disclosed and described herein;

FIG. 5B schematically depicts a cross section view of a self-heating personal covering comprising an insulating layer according to embodiments disclosed and described herein;

FIG. 6 schematically depicts a cross section view of a self-heating personal covering comprising thermally conductive material according to embodiments disclosed and described herein; and

FIG. 7 schematically depicts a cross section view of a self-heating personal covering comprising a layer of phase change material according to embodiments disclosed and described herein.

DETAILED DESCRIPTION

Reference will now be made in detail to embodiments of self-heating personal coverings, embodiments of which are illustrated in the accompanying drawings. Whenever possible, the same reference numerals will be used throughout the drawings to refer to the same or like parts. In one embodiment, a self-heating personal covering includes a first layer and a second layer that is parallel to and opposite of the first layer, and at least a portion of the second layer is fastened to at least a portion of the first layer. The self-heating personal covering also includes at least one heat source positioned between the first layer and the second layer. The at least one heat source is held in a prescribed position by the first layer and the second layer, and includes a material that undergoes an exothermic reaction upon exposure to oxygen. The at least one heat distributing structure is thermally connected to the at least one heat source. Various embodiments of self-heating personal coverings will be described herein with specific reference to the appended drawings. It should be understood that various elements within one embodiment of a self-heating personal covering may be incorporated in whole or in part to other embodiments of self-heating personal coverings.

As used herein, “personal coverings” includes, but is not limited to blankets, garments, gowns, wrappings, and dressings.

As used herein, “heat distributing structure” includes thermally conductive materials and thermally insulating materials.

A recently explored approach for heating personal coverings is to place self-heating materials into the personal coverings as heat sources. These self-heating materials are activated upon exposure to oxygen and undergo an exothermic reaction, thereby heating the personal covering. However, these self-heating materials can take an unacceptably long time to heat the personal covering to a temperature that will improve patient comfort or to maintain a patient's body temperature at an acceptable level. Also, the exothermic reactions of some self-heating materials may cause the self-heating materials to heat to a temperature that is above the target temperature for a personal covering, which may cause injury to a patient as well as damage to the personal covering. Further, these self-heating materials can create uneven heating and hot spots in the personal covering that leaves some portions of a patient's body overheated and some portions of a patient's body under heated, leading to discomfort.

The present disclosure is directed to a self-heating personal covering that comprises a plurality of heat sources positioned between a first and a second fabric layers. The heat sources may be spaced apart from one another in an array that may be a geometric array of evenly or unevenly spaced apart heat sources. Thermally conductive material may be positioned adjacent, and thermally connected to, one or more heat sources in the personal covering. The thermally conductive material may do one or both of direct heat generated at a heat source in a specific direction—such as, for example, toward a patient—and dissipate heat from the heat source throughout the personal covering.

The self-heating personal covering may be packaged in an air-tight packaging that prevents oxygen from contacting the heat source prior to use, thereby preventing the heat source from undergoing an unwanted exothermic reaction. This packaging configuration allows self-heating person covering to be stored for extended periods of time and allows the user to begin the exothermic reaction of the heat source as desired. Exercising this control over the exothermic reaction through the packaging configuration of the heat source allows the self-heating personal covering to be used on demand in any environment, and the self-heating personal covering will provide heat for several hours after the exothermic reaction of the heat source begins. The vacuum packaging in an air-tight package also compresses the personal blanket and, thus, more blankets can be stored in a given space. This allows more convenient access to the blankets at the bedside, and it also reduces the cost of shipping and storage space.

Because the self-heating personal covering does not require external energy to provide heat and because the self-heating personal covering can provide heat for several hours, the self-heating personal covering may be transported with the patent from the field to an examination room or operating room, and beyond without interruption in heating, the need to transport other machinery, or the need for multiple personal coverings.

Depicted in FIG. 1 schematically depicts a top view of a self-heating personal covering 100 according to one or more embodiments shown and described herein. In the embodiment depicted in FIG. 1, the self-heating personal covering 100 is a blanket that has a generally rectangular shape. In other embodiments, the self-heating personal covering 100 may be a gown, a wrap, or another type of covering. In embodiments, the self-heating personal covering 100 may have a geometry other than rectangular, such as a circle, an oval, or any other symmetrical or asymmetrical geometry. The self-heating personal covering 100 of the embodiment depicted in FIG. 1 comprises a first layer 110 that is made from a pliable fabric. The pliable fabric that forms the first layer 110 should, in embodiments, be made from a fabric that is flexible enough to drape over a patient, easily bend to conform to the shape of a patient, and move with a patient as a patient moves or is transported. The pliable fabric that forms the first layer 110 may, in embodiments, be made from woven or non-woven materials and, in one or more embodiments, is made from a non-woven material. Woven materials that may be used as the pliable fabric of the first layer 110 include wool, cotton, polyester, and mixtures thereof and the like. In some embodiments of the self-heating personal covering 100 a non-woven material is used as the first layer 110 to reduce the cost of the self-heating personal covering 100. In embodiments where the first layer 110 is made from a non-woven material, the first layer 110 may be made from polyethylene, polypropylene, polyamide, polyester, polyacrylonitrile, acrylic, rayon, acetate and viscose filaments, or the like. The non-woven material may include a cotton blend to improve tactile comfort.

With reference to the embodiment depicted in FIG. 1, the first layer 110 of the self-heating personal covering 100 is positioned adjacent to a plurality of heat sources 120 that are arranged in an array. It should be understood that the plurality of heat sources 120 is not visible from the top view because the plurality of heat sources 120 is covered by the first layer 110. In some embodiments, the first layer 110 physically contacts the heat sources 120. In other embodiments, the first layer 110 does not physically contact the heat sources 120, and is physically separated from the heat sources 120 by other layers positioned between the first layer 110 and the heat sources 120 or by a gap or void between the first layer 110 and the heat sources 120.

FIG. 2 is a schematic cross section view of the embodiment depicted in FIG. 1 along the line A. As shown in FIG. 2, the heat sources 120 are positioned between the first layer 110 and a second layer 130 that is positioned parallel to and opposite of the first layer 110. The second layer 130, according to some embodiments, may be made from the same or a different material than the first layer 110. For instance, in some embodiments, the first layer 110 may be made from nonwoven material and the second layer 130 may be made from a woven material. In other embodiments, the first layer 110 may be made from a first nonwoven material and the second layer 130 may be made from a second nonwoven material. Or, in yet another embodiment, the first layer 110 and the second layer 130 may be made from the same nonwoven material. It should be understood that other combinations of materials may be used to form the first layer 110 and the second layer 130, and the combinations that may be used are not limited.

In the embodiment depicted in FIG. 2 the first layer 110 and the second layer 130 physically contact the heat sources 120. In other embodiments, and as discussed above, the first layer 110 and the second layer 130 may not physically contact the heat sources 120 and may be physically separated from the heat sources 120 by additional layers, which will be described in more detail below, or a void or gap positioned between the heat sources 120 and one or both of the first layer 110 and the second layer 130. In some embodiments, such as the embodiment depicted in FIG. 2, the first layer 110 and the second layer 130 may be fastened together on either end of the self-heating person covering 100 and between one or more of the heat sources 120. For instance, as shown in FIG. 2, the first layer 110 may be fastened to the second layer 130 at a first end 101 of the self-heating personal covering and at a second end 102 of the self-heating personal covering. In addition, and as also shown in the embodiment depicted in FIG. 2, the first layer 110 may be fastened to the second layer 130 between each of the three heat sources 120. By fastening the first layer 110 and the second layer 130 between each of the heat sources 120 secures each of the heat sources 120 in place so that they do not move during use of the self-heating personal covering 100 and alter the positioning of the heat sources 120. In embodiments, the first layer 110 and the second layer 130 can be fastened together by any suitable method, such as, for example, mechanical methods (such as stitching or riveting), heating methods (such as ultrasonic or RF welding), or chemical methods (such as gluing).

With reference again to FIG. 1, although the heat sources 120 are shaped as rectangles, it should be understood that, in one or more embodiments, the heat sources 120 may be of any shape. For instance, oval-shaped heat sources may be used to mimic the shapes of a patient's appendages, or a circular heat source may be used to mimic the shape of a patient's torso. In addition, the size of the heat sources 120 may, in one or more embodiments, be the same as or different from the size of the heat sources of embodiments depicted in FIG. 1 relative to the size of the self-heating personal covering 100. The size of the heat sources 120 may vary in embodiments based on the size and shape of the self-heating personal covering, the geometry in which the plurality of heat sources 120 are arranged, or the type of self-heating personal covering in which the heat sources 120 are incorporated (e.g., a blanket, a gown, a wrap, a dressing, etc.).

The heat sources 120 may comprise a material that undergoes an exothermic reaction upon exposure to oxygen, such as, for example, upon exposure to ambient atmosphere. Materials commonly used in such heat sources, according to some embodiments, include iron that reacts with oxygen in an exothermic reaction to form iron oxide. Commercially available iron-containing materials used for this purpose include, for example, Pfizer Thermacare® heat wraps, Ready-Heat blanket by TechTrade, and hand warmers by HotHands®, Heat Factory®, HeatMax, Grabber®, Yatktrax®, Little Hotties®, and Ergodyne N-Ferno®. Other materials that, according to one or more embodiments, may be used in the heat sources 120 that undergo an exothermic reaction upon exposure to oxygen include zinc and aluminum, which may be alone or in combination, and react to form zinc oxide and aluminum oxide, respectively, when exposed to oxygen. When using zinc and/or aluminum in the heat sources 120 a carbon may be included as a reduction promoter for oxygen, an alkaline electrolyte may be included as a catalyst to trigger the reaction, and a polytetrafluoroethylene (PTFE) binding agent may be included in the material of the heat sources 120. Commercially available zinc and/or aluminum containing materials used for this purpose include, for example, Exothermix™. However, it should be understood that in embodiments of self-heating personal coverings disclosed and described herein, the heat sources of the self-heating personal coverings may include other materials that undergo an exothermic reaction upon exposure to oxygen in addition to, or as a replacement of, the materials subsequently disclosed.

Because, in embodiments, the heat sources 120 include materials that require exposure to oxygen to begin an exothermic reaction that generates heat, the first layer 110 and the second layer 130 should, in embodiments, provide permeability that allows air and/or oxygen access to the heat sources when desired. In some embodiments, the vapor permeability will be from greater than or equal to 30% to less than or equal to 100%, such as greater than or equal to 35% to less than or equal to 100%, greater than or equal to 40% to less than or equal to 100%, greater than or equal to 45% to less than or equal to 100%, greater than or equal to 50% to less than or equal to 100%, greater than or equal to 55% to less than or equal to 100%, greater than or equal to 60% to less than or equal to 100%, greater than or equal to 65% to less than or equal to 100%, greater than or equal to 70% to less than or equal to 100%, greater than or equal to 75% to less than or equal to 100%, greater than or equal to 80% to less than or equal to 100%, greater than or equal to 85% to less than or equal to 100%, greater than or equal to 90% to less than or equal to 100%, or greater than or equal to 95% to less than or equal to 100%. In other embodiments the vapor permeability is from greater than or equal to 30% to less than or equal to 95%, such as greater than or equal to 30% to less than or equal to 90%, greater than or equal to 30% to less than or equal to 85%, greater than or equal to 30% to less than or equal to 80%, greater than or equal to 30% to less than or equal to 75%, greater than or equal to 30% to less than or equal to 70%, greater than or equal to 30% to less than or equal to 65%, greater than or equal to 30% to less than or equal to 60%, greater than or equal to 30% to less than or equal to 55%, greater than or equal to 30% to less than or equal to 50%, greater than or equal to 30% to less than or equal to 45%, greater than or equal to 30% to less than or equal to 40%, or greater than or equal to 30% to less than or equal to 35%. Materials may have the desired permeability include, for example, paper, polyethylene, polypropylene, polyamide, polyester, polyvinyl chloride, polyvinylidene chloride, polyurethane, polystyrene, saponified ethylene-vinyl acetate copolymer, ethylene-vinyl acetate copolymer, natural rubber, reclaimed rubber, synthetic rubber, and mixtures thereof.

As discussed above, the self-heating personal covering 100 may be placed in an air-tight packaging that restricts access of air and/or oxygen to the self-hating personal covering until the air-tight package is opened. Thereby, a user may determine when to begin the heating of the self-heating personal covering 100, and the self-heating personal covering 100 may be stored for an extended period of time.

FIG. 3 is a graph that shows the activity time and heating duration of various commercially available materials that undergo an exothermic reaction upon exposure to oxygen. The y-axis in the graph of FIG. 3 shows the temperature of the material in degrees Celsius (° C.), and the x-axis in the graph of FIG. 3 shows the time in minutes. In FIG. 3 40° C. is marked across the graph because 40° C. is generally considered to be within the optimal temperature range for a heating apparatus used to increase a patient's body temperature. Temperatures above 42° C. can increase risk of skin injury; temperatures above 38° C. may feel too warm; temperatures below 38° C. have limited capability to increase a patient's body temperature; and temperatures below 34° C. can make a patient feel cold. Accordingly, one parameter to consider when selecting a material to use in a heat source of a self-heating personal covering is the duration that the material provides heat to the self-heating personal covering at temperatures above 40° C. As shown in FIG. 3 all four of the materials tested provide heat at or above 40° C. for a duration of at least 90 minutes. In some embodiments, materials may be used in a heat source of a self-heating personal covering that provide heat at or above 40° C. for durations of greater than or equal to 90 minutes, such as greater than or equal to 120 minutes, greater than or equal to 150 minutes, or even greater than or equal to 180 minutes.

Another parameter to consider for materials that may be used in heat sources for the self-heating personal coverings according to embodiments is the time that it takes the material to heat to 40° C. after initial exposure to oxygen. When a patient's body temperature drops below acceptable limits, such as when the patient is in shock or suffering from hypothermia, it is important to increase the patient's body temperature as quickly as possible to avoid negative effects of a reduced body temperature. In addition, patients waiting for surgery often feel cold even if their body temperature is normal, due to their emotional state. Further, these patients may wait as short as 15 minutes for surgery. Thus, every minute that it takes a material to heat to 40° C. can have an effect on patient outcomes, as well as patient satisfaction. As shown in FIG. 3 three of the four tested materials—Ready Heat II EMS blanket material, Ready Heat blanket material, and Pfizer Thermacare® wraps material—take 14 minutes or longer to reach 40° C. In many instances, such a heating time may be unacceptable. The material used in Exothermix™ products heat to 40° C. in approximately three minutes, which is a dramatic improvement over the other tested materials. However, the materials used in Exothermix™ products heat very rapidly to high temperatures around 60° C., which can be too warm for many applications and, if the heat source is focused on a concentrated area can cause discomfort to a patient.

To use materials as a heat source that quickly heat to 40° C., the heat sources in a self-heating personal covering should be properly spaced apart to prevent overheating of the self-heating personal covering. With reference again to the embodiment depicted in FIG. 1, the plurality of heat sources 120 is arranged in a symmetrical geometric array of evenly spaced-apart heat sources comprising three columns and six rows. It should be understood that in other embodiments, the plurality of heat sources 120 may comprise more or less heat sources than the 18 heat sources depicted in FIG. 1. In addition, in one or more embodiments, the plurality of heat sources 120 may be arranged in an asymmetrical array. For instance, FIG. 4 schematically depicts a top view of a self-heating personal covering 400 having a plurality of heat sources 120 an asymmetrical array that mimics the outline of a human body. It should be understood that any geometrical array of the plurality of heat sources 120 are within the scope and embodiments of this disclosure. Additionally, in embodiments, the plurality of heat sources 120 may include any number of heat sources 120. For instance, in self-heating personal coverings according to some embodiments, it may be desirable to provide heat only to the torso of a patient's body. In such embodiments, the plurality of heat sources 120 may only be present in middle of a self-heating personal covering that corresponds to the patient's torso. In other embodiments. In addition, in embodiments where the self-heating personal covering is a gown, wrap, or dressing, the number and arrangement of the plurality of heat sources may be configured to coincide with the size and shape of the gown, wrap, or dressing. Accordingly, in some embodiments, only one heat source may be included in the self-hating personal covering, such as, for example, where a heat source is present in a small wrap or dressing. For example, a dressing could be used to trigger general feelings of thermal comfort through application in local areas with high thermal sensitivity such as the feet, hands, wrists, neck, face, and head.

With reference again to the embodiment depicted in FIG. 1, the plurality of heat sources 120 are arranged into a symmetric geometrical pattern of three columns and six rows. Although the spacing between the columns and rows of heat sources 120 is not limited in this disclosure, in embodiments, the spacing between rows may be greater than or equal to 3.0 inches (7.62 cm), such as greater than or equal to 3.5 inches (8.89 cm), greater than or equal to 4.0 inches (10.16 cm), greater than or equal to 4.5 inches (11.43 cm), or greater than or equal to 5.0 inches (12.70 cm). In some embodiments, the spacing between rows of heat sources 120 in the array of heat sources may be less than or equal to 6.0 inches (15.24 cm), less than or equal to 5.5 inches (13.97 cm), less than or equal to 5.0 inches (12.70 cm), or less than or equal to 4.5 inches (11.43 cm). In embodiments, the spacing between columns of heat sources 120 in the array of heat sources may be greater than or equal to 6.0 inches (15.24 cm), greater than or equal to 6.5 inches (16.51 cm), greater than or equal to 7.0 inches (17.78 cm), or greater than or equal to 7.5 inches (19.05 cm). In embodiments, the spacing between rows of heat sources 120 in the array of heat sources may be less than or equal to 8.0 inches (20.32 cm), less than or equal to 7.5 inches (19.05 cm), less than or equal to 7.0 inches (17.78 cm), or less than or equal to 6.5 inches (16.51 cm).

Although not depicted, the plurality of heat sources 120 may be arranged into an array having a symmetrical geometry pattern of four columns and six rows. In embodiments, the spacing between rows may be greater than or equal to 3.0 inches (7.62 cm), such as greater than or equal to 3.5 inches (8.89 cm), greater than or equal to 4.0 inches (10.16 cm), greater than or equal to 4.5 inches (11.43 cm), or greater than or equal to 5.0 inches (12.70 cm). In some embodiments, the spacing between rows of heat sources 120 in the array of heat sources may be less than or equal to 6.0 inches (15.24 cm), less than or equal to 5.5 inches (13.97 cm), less than or equal to 5.0 inches (12.70 cm), or less than or equal to 4.5 inches (11.43 cm). In embodiments, the spacing between columns of heat sources 120 in the array of heat sources may be greater than or equal to 2.0 inches (5.08 cm), greater than or equal to 2.5 inches (6.35 cm), greater than or equal to 3.0 inches (7.62 cm), or greater than or equal to 3.5 inches (8.89 cm). In embodiments, the spacing between rows of heat sources 120 in the array of heat sources may be less than or equal to 4.0 inches (10.16 cm), less than or equal to 3.5 inches (8.89 cm), or less than or equal to 3.0 inches (7.62 cm).

Because the heat sources 120 are primary drivers of the cost of self-heating personal coverings 100 according to embodiments, having heat sources 120 arranged in a symmetric or asymmetric geometrical array with spacing between the heat sources 120 allows the cost of the self-heating personal coverings 100 to be minimized while still providing adequate heating. However, having such spacing between heat sources 120 in the geometrical array of heat sources can cause heat losses and/or provide uneven distribution of heat across the self-heating personal covering 100. Accordingly, to prevent heat losses and/or provide improved, even distribution of heat generated by the plurality of heat sources 120 in the self-heating personal covering 100, one or more heat distributing structures may be incorporated into the self-heating personal covering 100 proximate to and in thermal connectivity with the heat sources 120. The one or more heat-distributing structures according to one or more embodiments disclosed and described herein include insulating materials, thermally conductive materials, and or phase change materials that may be strategically positioned in proximity to the heat sources 120.

With reference to FIG. 5A and FIG. 5B, which are schematic depictions of a cross section of a self-heating personal covering 500 according to embodiments disclosed and described herein, an insulating layer 510 may be positioned adjacent to the heat sources 120. The embodiment depicted in FIG. 5A comprises a first layer 110 and a second layer 130 that can be compositionally and structurally identical to the first layer and second layer described above. A plurality of heat sources 120 are positioned between the first layer 110 and the second layer 130 such that the first layer 110 and the second layer 130 hold the plurality of heat sources 120 in place. Additionally, in the embodiments depicted in FIG. 5A and FIG. 5B, an insulating layer 510 is positioned between the plurality of heat sources 120 and the first layer 110 and is thermally connected to the plurality of heat sources 120. In such embodiments, the first layer 110 may be positioned away from the patient so that the patient is nearest to the second layer 130 and the first layer 110 is either exposed to the air or other coverings (such as, for example blankets, gowns, etc.). In such embodiments, the insulating layer 510 prevents heat from escaping through the first layer 110 and away from a patient. The insulating layer 510 also directs the heat into air gaps 520 positioned between the heat sources 120 to improve the evenness of heat distribution from the heat sources 120 across the self-heating personal covering 500. For instance, because the insulating layer 510 directs heat to the air gaps 520 within the self-heating personal covering, a temperature difference between the heat sources 120 and the air gaps 520 between the heat sources 120 will be less than a temperature difference between the heat sources 120 and the air gaps 520 if there were no insulating layer 510 present. Accordingly, a more even distribution of heat across the self-heating personal covering 500 may be achieved by including an insulating layer, such as the insulating layer 510 in the embodiments depicted in FIG. 5A and FIG. 5B.

It should be understood that although the embodiment depicted in FIG. 5A shows the insulating layer 510 as a separate layer, in other embodiments, insulating material may be incorporated into the first layer 110 to provide the same or similar effect as a distinct insulating layer.

In the embodiment depicted in FIG. 5A, the insulating layer 510 is a continuous insulating layer that is positioned between the first layer 110 and the plurality of heat sources 120. This configuration may restrict access of air to the plurality of heat sources 120, thereby limiting the extent of the exothermic reaction of the material in the heat sources 120. Although limiting the extent of the exothermic reaction that occurs within the heat sources 120 may be beneficial to prevent the temperature of the self-heating personal covering 500 from getting to high, limiting of the extent of the exothermic reaction that occurs within the heat sources 120 can keep the self-heating personal covering 500 from heating quickly or reaching the desired temperature (such as about 40° C.). Accordingly, in one or more embodiments, the material that comprises the insulating layer 510 (or the insulating material incorporated within the first layer 110) may be a material that is air and/or oxygen permeable, and allows air to traverse through the insulating layer 510 (or the first layer 110) to the heat sources 120, thereby allowing exothermic reactions to occur within the heat sources 120 relatively unencumbered. Using air and/or oxygen permeable materials will also allow for some control over the extent of the exothermic reaction that occurs at the heat sources. For instance, in embodiments where an insulating material having a high air and/or oxygen permeability is used in the insulating layer 510 (or as the insulating material in the first layer 110), the extent of the exothermic reaction that occurs within the heat sources will be high. However, in embodiments where an insulating material having a low air and/or oxygen permeability is used in the insulating layer 510 (or as the insulating material in the first layer 110), the extent of the exothermic reaction that occurs within the heat sources will be low. Accordingly, in embodiments, the extent of the exothermic reaction that occurs within the plurality of heat sources 120 may be controlled, at least in part, by the materials selected for use in the insulating layer 510 (or used as insulating material in the first layer 110).

In one or more embodiments, and as shown in the embodiment depicted in FIG. 5B, the amount of air and/or oxygen that accesses the heat sources 120 may be controlled by forming physical channels 530 within the insulating layer 510. The channels 530 allow air and/or oxygen to access the heat sources 120 and may be sized and positioned such that a significant amount of heat is not permitted to escape through the channels 530 or the insulating layer 510. Although the embodiment depicted in FIG. 5B shows a certain size and configuration of the channels 530 within the insulating layer 510, it should be understood that embodiments are not limited to this size and configuration of channels 530 within the insulating layer 510.

Although embodiments depicted in FIG. 5A and FIG. 5B show an insulating layer 510 positioned between the first layer 110 and the heat sources 120, in other embodiments that are not depicted, an insulating layer may be positioned between the heat sources 120 and the second layer 130, or insulating material may be incorporated into the second layer 130. In various embodiments, this insulating layer positioned between the heat sources 120 and the second layer 130 (or insulating material incorporated into the second layer 130) may be used with or without an insulating layer 510 positioned between the first layer 110 and the heat sources 120 (or with insulating material incorporated into the first layer 110). Although such a configuration of the insulating layer may allow heat to escape from the self-heating personal covering 500 through the first layer 110, such a configuration may also prevent a patient from being exposed to high temperatures if the heat sources generate too much heat.

In some embodiments, an insulating layer may be positioned only physically between the heat sources 120 and the second layer 130 and the insulating layer will not be present between the air gaps 520 and the second layer 130. This configuration may prevent a patient from being exposed to high temperatures of the heat sources 120 while directing the heat into the air gaps 520, thereby improving even heat distribution within the self-heating personal covering 500.

As used herein, an “insulating” material is a material that conducts heat at a rate lower than or equal to air (which has a thermal conductivity of 0.024 W/(m-K) at 25° C.). Although the insulating material used in the insulating layer 510 or in the first layer 110 of the self-heating personal covering 500 is not limited, in some embodiments the insulating material may be selected from open cell foams, such as, for example, Microcell™ foam, PrimaLoft®, Polarguard®, Climashield®, Thinsulate™, Insultex®, cotton batting, polyester fibers, and combinations thereof. It should be understood that the insulating layer 510 may be mixed with materials that are not insulating materials. Accordingly, in embodiments, the insulating layer 510 may comprise, consist essentially of, or consist of insulating materials.

Additionally, in some embodiments an insulating layer may include a reflective insulating layer, such as, for example, Mylar®, and other polyester films made from stretched polyethylene terephthalate (PET), including Biaxially-oriented polyethylene terephthalate (BoPET). In one or more embodiments, this reflective insulating layer is positioned between the heat source and the layer that is configured to be nearest a patient. For instance, and with reference to FIG. 5A, where a first layer 110 of the self-heating personal covering 500 is configured to be positioned nearest to a patient, the insulating layer 510 may be a reflective insulating layer.

With reference now to the embodiment depicted in FIG. 6, which is a schematic depiction of a cross section of a self-heating personal covering according to embodiments disclosed an described herein, in addition to or as an alternative of the insulating layers described above, thermally conductive materials may be integrated into the self-heating personal covering 600 according to embodiments. Although the embodiment depicted in FIG. 6 does not include an insulating layer as described above, it should be understood that the thermally conductive materials described in the embodiment depicted in FIG. 6 may be incorporated into embodiments that comprise an insulating layer or insulating material incorporated into either the first layer 110 or the second layer 130 of the self-heating personal covering 600. As used herein, a “thermally conductive material” includes a material selected to quickly transfer heat, such as at a rate of greater than or equal to water (0.58 W/(m-K) at 25° C.).

The embodiment depicted in FIG. 6 comprises a first layer 110 and a second layer 130 that can be compositionally and structurally identical to the first layer and second layer described above. A plurality of heat sources 120 are positioned between the first layer 110 and the second layer 130 such that the first layer 110 and the second layer 130 hold the plurality of heat sources 120 in place. Additionally, in the embodiment depicted in FIG. 6, a thermally conductive material 610 is positioned between one or more of the plurality of heat sources 120 and is thermally connected to the plurality of heat sources 120. Also, thermally conductive material 610 may be positioned between heat sources 120 and a first end 101 of the self-heating personal covering 600, and thermally conductive material 610 may be positioned between heat sources 120 and a second end 102 of the self-heating personal covering 600. In such embodiments, the thermally conductive material 610 extracts heat from the heat sources 120 and distributes that heat into the positions between the heat sources 120, thereby increasing the even distribution of heat across the self-heating personal covering 600. By using the thermally conductive material 610 between the heat sources 120, heat may be better distributed across the self-heating personal covering using less heat sources 120 than would be required if thermally conductive material 610 is not positioned between the heat sources 120. Because the heat sources 120 generally cost more than thermally conductive materials 610, add weight to the self-heating personal covering 600, and are more bulky than thermally conductive materials 610, using thermally conductive materials 610 positioned between the heat sources 120 can reduce the cost, weight, and bulkiness of the self-heating personal covering 600.

Although the material used in the thermally conductive material 610 is not limited, in some embodiments the insulating material may be selected from the group consisting of high density polyethylene (HDPE) textiles, Tyvek™ nonwoven materials, metallic foils (such as, for example, aluminum foil and the like), and bladders filled with thermally conductive materials (such as, for example, silicone oil or air), and combinations thereof. As used herein, the term “thermally conductive materials” may also include materials with high specific heat, which, as used herein, includes materials with a specific heat greater than the specific heat of air (1.01 kJ/kg-K) and as close as possible to the specific heat of water (4.18 kJ/kg-K). It should be understood that the thermally conductive material 610 may be mixed with materials that are not thermally conductive. Accordingly, in embodiments, the layer thermally conductive material may comprise, consist essentially of, or consist of thermally conductive materials.

With reference now to the embodiment depicted in FIG. 7, which is a schematic depiction of a cross section of a self-heating personal covering according to embodiments disclosed an described herein, in addition to or as an alternative of the insulating layers and thermally conductive materials described above, a layer of phase change materials may be integrated into the self-heating personal covering 700 according to embodiments. Although the embodiment depicted in FIG. 7 does not include an insulating layer or thermally conductive materials as described above, it should be understood that the layer of phase change materials described in the embodiment depicted in FIG. 7 may be incorporated into embodiments that comprise an insulating layer (or insulating material incorporated into either the first layer 110 or the second layer 130 of the self-heating personal covering 700) or that include thermally conductive material.

The embodiment depicted in FIG. 7 comprises a first layer 110 and a second layer 130 that can be compositionally and structurally identical to the first layer and second layer described above. A plurality of heat sources 120 are positioned between the first layer 110 and the second layer 130 such that the first layer 110 and the second layer 130 hold the plurality of heat sources 120 in place. Additionally, in the embodiment depicted in FIG. 7, a layer of phase change material 710 positioned between the plurality of heat sources 120 and the second layer 130. In such embodiments, the layer of phase change material 710 extracts heat from the heat sources 120 and distributes that heat into the positions between the heat sources 120, thereby increasing the even distribution of heat across the self-heating personal covering 700. Although not shown in the embodiment depicted in FIG. 7, the layer of phase change material 710 may extend beyond the heat sources 120 toward, for example, a first end 101 and/or a second end 102 of the self-heating personal covering. This configuration allows less heat sources 120 to be used in the self-heating personal covering 700, thereby reducing the cost, weigh, and bulkiness of the self-heating personal covering, for the reasons discussed above.

Additionally, the layer of phase change material 710 between the heat sources 120 and the second layer 130 may prevent the likelihood of a patient overheating by absorbing heat while residing within the phase change temperature. In particular, without being bound to any particular theory, it is believed that the latent heat of fusion or phase change of the layer of phase change material 710 is about an order of magnitude higher than the heat released by non-phase change materials. Accordingly, the phase change materials used in the layer of phase change material 710 provides an energy reserve that may absorb excess heat if the heat sources 120 generate too much heat. Accordingly, in one or more embodiments, phase change materials for use in the layer of phase change material 710 may be selected based upon their latent heat of fusion to regulate the temperature of the self-heating personal covering 700.

Also, according to embodiments, the layer of phase change material 710 may also increase the duration at which the self-heating personal covering 700 provides heating to a temperature of within a desired range (such as about 40° C.). Without being bound to any particular theory, it is believed that this increased duration is accomplished by selecting a phase change material with a melting point around the desired temperature. As the phase change material slowly changes phases with a few degrees of this selected temperature, the self-heating personal covering 700 will likewise maintain a temperature near the selected temperature for a period after the heat sources 120 stop generating heat.

Although the material used in the layer of phase change material 710 is not limited, in some embodiments the material used in the layer of phase change material may be selected from the group consisting of paraffins, capric acid, trimyristin, caprylone, docasyl bromide, camphenilone, and combinations thereof. In one or more embodiments, microencapsulated phase change materials may be used. In some embodiments, the microencapsulated phase change materials may be incorporated into fibers, but in other embodiments the microencapsulated phase change materials may be suspended in a carrier oil, such as, for example, silicone oil.

It should be understood that the layer of phase change material 710 may include a mixture of phase change materials and materials that are not phase change materials. Accordingly, in embodiments, the layer of phase change material 710 may comprise, consist essentially or, or consist of phase change materials.

By using self-heating personal coverings according to embodiments disclosed and described herein that include heat distributing structures proximate to heat sources, heat sources that rapidly heat to about 40° C. may be used. These rapidly-heating heat sources allow self-heating personal coverings according to embodiments disclosed and described herein to heat to a desired temperature much more quickly than conventional self-heating personal coverings. Additionally, by incorporating heat distributing structure proximate to the heat sources, less heat sources need to be incorporated into the self-heating personal covering according to embodiments disclosed and described herein. This decreases the cost, weight, and bulkiness of the self-heating personal coverings. Additionally, the size of the heat sources themselves may be reduced, which allows the self-heating personal coverings according to embodiments disclosed and described herein to have less weight and bulkiness than conventional self-heating personal coverings.

For instance, in embodiments, the thickness of the self-heating personal covering may be less than or equal to 0.100 inches (0.254 cm), such as less than or equal to 0.095 inches (0.241 cm), less than or equal to 0.090 inches (0.229 cm), less than or equal to 0.085 inches (0.216 cm), or less than or equal to 0.080 inches (0.203 cm). Additionally, in one or more embodiments, the weight of the self-heating personal covering is less than or equal to 7.5 g/m², such as less than or equal to 7.0 g/m², less than or equal to 6.5 g/m², less than or equal to 6.0 g/m², less than or equal to 5.5 g/m², or less than or equal to 5.0 g/m².

According to a first clause, a self-heating personal covering comprises a first layer; a second layer parallel to and opposite of the first layer, wherein at least a portion of the second layer is fastened to at least a portion of the first layer; at least one heat source positioned between the first layer and the second layer, wherein the at least one heat source is held in a prescribed position by the first layer and the second layer, and the at least one heat source comprises a material that undergoes an exothermic reaction upon exposure to oxygen to generate heat; and at least one heat distributing structure that is thermally connected to the at least one heat source.

A second clause includes the self-heating personal covering of the first clause, wherein the at least one heat source comprises a plurality of heat sources arranged in a geometrically array, and the geometrical array of the plurality of heat sources comprises spacing between each heat source in the plurality of heat sources.

A third clause includes the self-heating personal covering of the first and second clause, wherein the at least one heat distributing structure is positioned so that a portion of the at last one heat distributing structure is present in the spacing between each heat source in the plurality of heat sources.

A fourth clause includes the self-heating personal covering of any one of the first through third clauses, wherein the at least one heat distributing structure comprises a plurality of heat distributing structures, and at least one heat distributing structure of the plurality of heat distributing structures is present in the spacing between each heat source in the plurality of heat sources.

A fifth clause includes the self-heating personal covering of any one of the first through fourth clauses, wherein the at least one heat distributing structure comprises an insulating material.

A sixth clause includes the self-heating personal covering of the fifth clause, wherein the insulating material is incorporated into the first layer.

A seventh clause includes the self-heating personal covering of the fifth clause, wherein the insulating material comprises an insulating layer that is positioned between the first layer and the at least one heat source.

An eighth clause includes the self-heating personal covering of the seventh clause, wherein the insulating layer comprises material that is permeable to oxygen.

A ninth clause includes the self-heating personal covering of any one of the seventh and eighth clauses, wherein the insulating layer comprises channels that permit oxygen to access the heat source.

A tenth clause includes any the self-heating personal covering of any one of the seventh through ninth clauses, wherein the at least one heat source comprises a first heat source and a second heat source, a gap comprising air is present in between the first heat source and the second heat source, and a portion of the insulating layer is positioned proximate to the first heat source, the second heat source, and the gap such that heat is directed into the gap between the first heat source and the second heat source.

An eleventh clause includes the self-heating personal covering of any one of the first through tenth clauses, wherein the heat distributing structure is a reflective insulating layer.

A twelfth clause includes the self-heating personal covering of any one of the first through eleventh clauses, wherein the at least one heat distributing structure comprises a thermally conductive material.

A thirteenth clause includes the self-heating personal covering of any one of the first through twelfth clauses, wherein the at least one heat source comprises a first heat source and a second heat source spaced apart from the first heat source, and the thermally conductive material is positioned between and thermally connected to the first heat source and the second heat source.

A fourteenth clause includes the self-heating personal covering of any one of the first through thirteenth clauses, wherein the thermally conductive material comprise a member selected from the group consisting of high density polyethylene (HDPE) textiles, metallic foils, bladders filled with thermally conductive materials, and combinations thereof.

A fifteenth clause includes the self-heating personal covering of any one of the first through fourteenth clauses, wherein the at least one heat distributing structure is a layer of phase change material.

A sixteenth clause includes the self-heating personal covering of any one of the first through fifteenth clauses, wherein the layer of phase change material is positioned between the at least one heat source and the second layer.

A seventeenth clause includes the self-heating personal covering of any one of the first through sixteenth clauses, wherein the at least one heat source comprises a first heat source and a second heat source, a gap comprising air is present in between the first heat source and the second heat source, and a portion of the layer of phase change material is positioned proximate to the first heat source, the second heat source, and the gap such that heat is directed into the gap between the first heat source and the second heat source.

An eighteenth clause includes the self-heating personal covering of any one of the first through seventeenth clauses, wherein the layer of phase change material is selected from the group consisting of paraffins, capric acid, trimyristin, caprylone, docasyl bromide, camphenilone, and combinations thereof.

A nineteenth clause includes the self-heating personal covering of any one of the first through eighteenth clauses, wherein the first layer comprises a material that is oxygen permeable.

A twentieth clause includes the self-heating personal covering of any one of the first through nineteenth clauses, wherein the self-heating personal covering is a blanket having a thickness of less than or equal to 0.100 inches and a weight of less than or equal to 7.5 g.

It will be apparent to those skilled in the art that various modifications and variations can be made to the embodiments described herein without departing from the spirit and scope of the claimed subject matter. Thus it is intended that the specification cover the modifications and variations of the various embodiments described herein provided such modification and variations come within the scope of the appended claims and their equivalents. 

What is claimed is:
 1. A self-heating personal covering comprising: a first layer; a second layer parallel to and opposite of the first layer, wherein at least a portion of the second layer is fastened to at least a portion of the first layer; at least one heat source positioned between the first layer and the second layer, wherein the at least one heat source is held in a prescribed position by the first layer and the second layer, and the at least one heat source comprises a material that undergoes an exothermic reaction upon exposure to oxygen to generate heat; and at least one heat distributing structure that is thermally connected to the at least one heat source.
 2. The self-heating personal covering of claim 1, wherein the at least one heat source comprises a plurality of heat sources arranged in a geometrical array, and the geometrical array of the plurality of heat sources comprises spacing between each heat source in the plurality of heat sources.
 3. The self-heating personal covering of claim 2, wherein the at least one heat distributing structure is positioned so that a portion of the at last one heat distributing structure is present in the spacing between each heat source in the plurality of heat sources.
 4. The self-heating personal covering of claim 2, wherein the at least one heat distributing structure comprises a plurality of heat distributing structures, and at least one heat distributing structure of the plurality of heat distributing structures is present in the spacing between each heat source in the plurality of heat sources.
 5. The self-heating personal covering of claim 1, wherein the at least one heat distributing structure comprises an insulating material.
 6. The self-heating personal covering of claim 5, wherein the insulating material is incorporated into the first layer.
 7. The self-heating personal covering of claim 5, wherein the insulating material comprises an insulating layer that is positioned between the first layer and the at least one heat source.
 8. The self-heating personal covering of claim 7, wherein the insulating layer comprises material that is permeable to oxygen.
 9. The self-heating personal covering of claim 7, wherein the insulating layer comprises channels that permit oxygen to access the at least one heat source.
 10. The self-heating personal covering of claim 7, wherein the at least one heat source comprises a first heat source and a second heat source, a gap comprising air is present in between the first heat source and the second heat source, and a portion of the insulating layer is positioned proximate to the first heat source, the second heat source, and the gap such that heat is directed into the gap between the first heat source and the second heat source.
 11. The self-heating personal covering of claim 5, wherein the insulating material is a reflective insulating material.
 12. The self-heating personal covering of claim 1, wherein the at least one heat distributing structure comprises a thermally conductive material.
 13. The self-heating personal covering of claim 12, wherein the at least one heat source comprises a first heat source and a second heat source spaced apart from the first heat source, and the thermally conductive material is positioned between and thermally connected to the first heat source and the second heat source.
 14. The self-heating personal covering of claim 12, wherein the thermally conductive material comprise a member selected from the group consisting of high density polyethylene (HDPE) textiles, metallic foils, bladders filled with thermally conductive materials or air, and combinations thereof.
 15. The self-heating personal covering of claim 1, wherein the at least one heat distributing structure is a layer of phase change material.
 16. The self-heating personal covering of claim 15, wherein the layer of phase change material is positioned between the at least one heat source and the second layer.
 17. The self-heating personal covering of claim 16, wherein the at least one heat source comprises a first heat source and a second heat source, a gap comprising air is present in between the first heat source and the second heat source, and a portion of the layer of phase change material is positioned proximate to the first heat source, the second heat source, and the gap such that heat is directed into the gap between the first heat source and the second heat source.
 18. The self-heating personal covering of claim 15, wherein the layer of phase change material is selected from the group consisting of paraffins, capric acid, trimyristin, caprylone, docasyl bromide, camphenilone, and combinations thereof.
 19. The self-heating personal covering of claim 1, wherein the first layer comprises a material that is oxygen permeable.
 20. The self-heating personal covering of claim 1, wherein the self-heating personal covering is a blanket having a thickness of less than or equal to 0.100 inches and a weight of less than or equal to 7.5 g/m². 